The present invention relates to a recording method and a reproducing method for recording or reproducing data on or from a recording medium such as an optical disk, a magneto-optical disk, a magnetic disk (hard disk) or the like and a recording apparatus a reproducing apparatus to which the recording method and the reproducing method are applicable.
A variety of recording apparatus and reproducing apparatus using an optical disk have heretofore been commercially available. Such recording apparatus and reproducing apparatus are able to record binary data (digital data of 1 or 0) modulated in a predetermined format by forming pits on the surface of a disk, for example. Upon reproduction, the existence of pits is detected from a reflected-back light of laser light or beam irradiated on the disk surface and the binary data thus recorded is reproduced.
Also, there have hitherto been known a recording apparatus and a reproducing apparatus using a disk called a magneto-optical disk in which a magnetization film in which information is recorded in the magnetization direction is formed as a recording film, information is recorded on the recording film at the position irradiated with a laser beam under the condition that a modulated magnetic field is generated and upon reproduction, recorded information is reproduced by detecting a change corresponding to the magnetization direction of a reflectance of laser beam. In this specification, an optical disk refers to a disk that may be recorded or reproduced by laser beam and includes a magneto-optical disk and a phase-change disk.
When information is recorded on an optical disk or information recorded on the optical disk is reproduced, information is recorded on the track located at the scanned position by scanning tracks of spiral-shape formed on the disk or information is reproduced from the track located at the scanned position. Therefore, fundamentally, a set of information are recorded on the scanned track or a set of information are reproduced from the scanned track. For this reason, information of a plurality of systems cannot be recorded on a plurality of different tracks simultaneously or information that are recorded on a plurality of different tracks cannot be reproduced simultaneously.
Also, when information is recorded on the optical disk, it is frequently intended to confirm by reproduction whether or not such information is recorded reliably. In such case, after the recording of information was ended, the recorded portion should be reproduced. There is then the problem that a time the duration of which is the same as that required by the recording is required in order to reproduce the recorded portion for confirming whether or not information was recorded positively.
If there are provided a plurality of optical pickups and laser beams from the plurality of optical pickups are irradiated on respective separate tracks on the optical disk, then information can be recorded on or reproduced from a plurality of tracks simultaneously. Also, it becomes possible to reproduce information, which was just recorded by a laser beam from one optical pickup, by a laser beam from other optical pickup. However, if there are provided a plurality of optical pickups, then assemblies used as an optical disk apparatus increase unavoidably, and all laser beams that are irradiated on respective tracks from the plurality of optical pickups should be properly servo-controlled. As a consequence, an arrangement of such servo-control system becomes complicated considerably.
While the problem, which encountered with the prior art when the optical disk is recorded and reproduced, has been described so far, a similar problem will arise when information is recorded on and reproduced from a variety of recording media.